Adding a last message id for selenium testing (#5840)

webapp/components/post_view/components/post.jsx

@@ -283,6 +283,7 @@ export default class Post extends React.Component {
                                 post={post}
                                 currentUser={this.props.currentUser}
                                 sameRoot={this.props.sameRoot}
+                                isLastPost={this.props.isLastPost}
                                 parentPost={parentPost}
                                 handleCommentClick={this.handleCommentClick}
                                 compactDisplay={this.props.compactDisplay}
@@ -305,6 +306,7 @@ Post.propTypes = {
     sameUser: React.PropTypes.bool,
     sameRoot: React.PropTypes.bool,
     hideProfilePic: React.PropTypes.bool,
+    isLastPost: React.PropTypes.bool,
     isLastComment: React.PropTypes.bool,
     shouldHighlight: React.PropTypes.bool,
     displayNameType: React.PropTypes.string,

webapp/components/post_view/components/post_body.jsx

@@ -163,7 +163,10 @@ export default class PostBody extends React.Component {
                 className={postClass}
             >
                 {loading}
-                <PostMessageContainer post={this.props.post}/>
+                <PostMessageContainer
+                    isLastPost={this.props.isLastPost}
+                    post={this.props.post}
+                />
             </div>
         );
 
@@ -208,6 +211,7 @@ PostBody.propTypes = {
     currentUser: React.PropTypes.object.isRequired,
     parentPost: React.PropTypes.object,
     retryPost: React.PropTypes.func,
+    isLastPost: React.PropTypes.bool,
     handleCommentClick: React.PropTypes.func.isRequired,
     compactDisplay: React.PropTypes.bool,
     previewCollapsed: React.PropTypes.string,

webapp/components/post_view/components/post_list.jsx

@@ -331,6 +331,7 @@ export default class PostList extends React.Component {
                 <Post
                     key={keyPrefix + 'postKey'}
                     ref={post.id}
+                    isLastPost={i === 0}
                     sameUser={sameUser}
                     sameRoot={sameRoot}
                     post={post}

webapp/components/post_view/components/post_message_container.jsx

@@ -15,7 +15,8 @@ import PostMessageView from './post_message_view.jsx';
 export default class PostMessageContainer extends React.Component {
     static propTypes = {
         post: React.PropTypes.object.isRequired,
-        options: React.PropTypes.object
+        options: React.PropTypes.object,
+        isLastPost: React.PropTypes.bool
     };
 
     static defaultProps = {
@@ -90,6 +91,7 @@ export default class PostMessageContainer extends React.Component {
             <PostMessageView
                 options={this.props.options}
                 post={this.props.post}
+                isLastPost={this.props.isLastPost}
                 emojis={this.state.emojis}
                 enableFormatting={this.state.enableFormatting}
                 mentionKeys={this.state.mentionKeys}

webapp/components/post_view/components/post_message_view.jsx

@@ -21,7 +21,8 @@ export default class PostMessageView extends React.Component {
         mentionKeys: React.PropTypes.arrayOf(React.PropTypes.string).isRequired,
         usernameMap: React.PropTypes.object.isRequired,
         channelNamesMap: React.PropTypes.object.isRequired,
-        team: React.PropTypes.object.isRequired
+        team: React.PropTypes.object.isRequired,
+        isLastPost: React.PropTypes.bool
     };
 
     shouldComponentUpdate(nextProps) {
@@ -113,6 +114,7 @@ export default class PostMessageView extends React.Component {
         return (
             <div>
                 <span
+                    id={this.props.isLastPost ? 'lastPostMessageText' : null}
                     className='post-message__text'
                     onClick={Utils.handleFormattedTextClick}
                     dangerouslySetInnerHTML={{__html: TextFormatting.formatText(this.props.post.message, options)}}